"...someone I saw at Sidmouth who was dressed from head to foot in red, or the those that wear copies of old agriculural smocks or fish-gutter's slops..."

How about the guest I saw at Keltic Lodge in Cape Breton, circa 1969? He was a young man from Oklahoma, without a drop of Scottish ancestry ('not that there's anything wrong with that!'), wearing a bright scarlet plaid outfit, pants, jacket and tie, playing a matching set of bagpipes. Certainly not 'scruffy', but oh my dear!